Abstract
Gradual hard X-ray/radio bursts are characterized by their long duration, smooth time profile, time delays between peaks at different hard X-ray energies and microwaves, and radiation from extended sources in the low and middle corona. Their characteristic properties have been ascribed to the dynamic evolution of the accelerated electrons in coronal magnetic traps or to the separate acceleration of high-energy electrons in a ‘second step’ process. The information available so far was drawn from qualitative considerations of time profiles or even only from the common occurrence of emissions in different spectral ranges. This paper presents model computations of the temporal evolution of hard X-ray and microwave spectra, together with a qualitative discussion of radio lightcurves over a wide spectral range, and metric imaging observations. The basic hypothesis investigated is that the peculiar ‘gradual’ features can be related to the dynamical evolution of electrons injected over an extended time interval in a coronal trap, with electrons up to relativistic energies being injected simultaneously. The analyzed event (26 April, 1981) is particularly challenging to this hypothesis because of the long time delays between peaks at different X-ray energies and microwave frequencies. The observations are shown to be consistent with the hypothesis, provided that the electrons lose their energy by Coulomb collisions and possibly betatron deceleration. The access of the electrons to different coronal structures varies in the course of the event. The evolution and likely destabilisation of part of the coronal plasma-magnetic field configuration is of crucial influence in determining the access to these structures and possibly the dynamical evolution of the trapped electrons through betatron deceleration in the late phase of the event.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Acton, L. W., Canfield, R. C., Gunkler, T. A., Hudson, H. S., Kiplinger, A. L., and Leibacher, J. W.: 1982,Astrophys. J. 263, 409.
Bai, T.: 1982, in R. E. Lingenfelter, H. S. Hudson, and D. M. Worall (eds.),Gamma-Ray Transients and Related Astrophysical Phenomena, A.I.P., New York, p. 315.
Bai, T. and Dennis, B. R.: 1985,Astrophys. J. 292, 699.
Bai, T. and Ramaty, R.: 1979,Astrophys. J. 219, 705.
Bai, T. and Sturrock, P. A.: 1989,Ann. Rev. Astron. Astrophys. 27, 421.
Bai, T., Hudson, H. S., Pelling, A. M., Lin, R. P., Schwartz, R. A., and von Rosenvinge, T. T.: 1983,Astrophys. J. 267, 433.
Cliver, E. W., Kahler, S. W., and McIntosh, P. S.: 1983,Astrophys. J. 264, 699.
Cliver, E. W., Dennis, B. R., Kiplinger, A. L., Kane, S. R., Neidig, D. F., Sheeley, N. R., Jr., and Koomen, M. J.: 1986,Astrophys. J. 305, 920.
De Jager, C. and de Jonge, G.: 1978,Solar Phys. 58, 127.
Dennis, B. R.: 1985,Solar Phys. 100, 465.
Dennis, B. R.: 1988,Solar Phys. 118, 49.
Dennis, B. R., Uberall, B. M., and Zarro, D.: 1991, in Z. Švestka, B. V. Jackson, and M. E. Machado (eds.),Eruptive Solar Flares, Lecture Notes in Physics 399, p. 199.
Doschek, G. A., Antiochos, S. K., Antonucci, E.et al.: 1986, in M. Kundu and B. Woodgate (eds.),Energetic Phenomena on the Sun, NASA-CP 2439.
Dulk, G. A.: 1973,Solar Phys. 32, 491.
Hernandez, A. M., Machado, M. E., Vilmer, N., and Trottet, G.: 1986,Astron. Astrophys. 167, 77.
Hulot, E., Vilmer, N., Chupp, E. L., Dennis, B. R., and Kane, S. R.: 1992,Astron. Astrophys. 256, 273.
Kahler, S. W.: 1984,Solar Phys. 90, 133.
Kai, K., Kosugi, T., and Nitta, N.: 1985,Publ. Astron. Soc. Japan 37, 105.
Kai, K., Nakajima, H., Kosugi, T., and Kane, S. R.: 1983,Solar Phys. 86, 231.
Kai, K., Nakajima, H., Kosugi, T., Stewart, R. T., Nelson, G. J., and Kane, S. R.: 1986,Solar Phys. 105, 393.
Kane, S. R., McTiernan, J., Loran, J., Fenimore, E. E., Klebesadel, R. W., and Loras, J. G.: 1992,Astrophys. J. 390, 687.
Kawabata, K., Ogawa, H., Takakura, T., Tsuneta, S., Ohki, K., Yoshimori, M., Okudaira, K., Hirashima, Y., and Kondo, I.: 1982,Hinotori Symp. on Solar Flares, ISAS, Japan, p. 168.
Klein, K.-L.: 1987,Astron. Astrophys. 183, 341.
Klein, K.-L., Trottet, G., and Magun, A.: 1986,Solar Phys. 104, 243.
Klein, K.-L., Anderson, K., Pick, M., Trottet, G., Vilmer, N., and Kane, S. R.: 1983,Solar Phys. 84, 295.
Klein, K.-L., Trottet, G., Benz, A., and Kane, S. R.: 1988,ESA-SP 285(1), 157.
Kosugi, T., Dennis, B. R., and Kai, K.: 1988,Astrophys. J. 324, 1118.
Kosugi, T., Kai, K., and Suzuki, T.: 1983,Solar Phys. 87, 373.
MacKinnon, A. L.: 1986,Astron. Astrophys. 163, 239.
MacKinnon, A. L., Brown, J. C., Trottet, G., and Vilmer, N.: 1983,Astron. Astrophys. 119, 297.
Nakajima, H.: 1983,Solar Phys. 86, 427.
Ohki, K., Takakura, T., Tsuneta, S., and Nitta, N.: 1983,Solar Phys. 86, 301.
Pallavicini, R., Serio, S., and Vaiana, G. S.: 1977,Astrophys. J. 216, 108.
Pick, M.: 1986,Solar Phys. 104, 19.
Ramaty, R.: 1969,Astrophys. J. 158, 753.
Takakura, T., Tsuneta, S., Ohki, K., Nitta, N., Nakishima, K., Murakami, T., Ogawara, Y., Oda, M., and Miyamoto, S.: 1983,Astrophys. J. 270, L83.
Tanaka, K.: 1987,Publ. Astron. Soc. Japan 39, 1.
Trottet, G.: 1986,Solar Phys. 104, 145.
Trottet, G. and Vilmer, N.: 1983,Proc. 18th Int. Cosmic Ray Conf., Bangalore, SP 3-15.
Trottet, G. and Vilmer, N.: 1984,Adv. Space Res. 4(7), 153.
Tsuneta, S., Takakura, T., Nitta, N., Ohki, K., Makishima, K., Murakami, T., Oda, M., and Ogawara, Y.: 1984,Astrophys. J. 280, 887.
Vilmer, N.: 1985, ‘Etude de l'accélération et du piégeage des électrons lors des éruptions solaires à partir des émissions de rayonnement X et radioélectriques’, thèse, Univ. de Paris VII, France.
Vilmer, N: 1987,Solar Phys. 111, 207.
Vilmer, N., Kane, S. R., and Trottet, G.: 1982,Astron. Astrophys. 108, 306.
Vilmer, N., MacKinnon, A. L., Klein, K.-L., and Trottet, G.: 1987,Proc. 20th Int. Cosmic Ray Conf., Moscow, SH-2.1-2.
Wentzel, D. G.: 1976,Astrophys. J. 208, 595.
Wu, S. T., de Jager, C., Dennis, B. R., Hudson, H. S.et al.: 1986, in M. Kundu and B. Woodgate (eds.),Energetic Phenomena on the Sun, NASA-CP 2439.
Yoshimori, M., Watanabe, H., and Nitta, N.: 1985,J. Phys. Soc. Japan 54, 4462.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Bruggmann, G., Vilmer, N., Klein, K.L. et al. Electron trapping in evolving coronal structures during a large gradual hard X-ray/radio burst. Sol Phys 149, 171–193 (1994). https://doi.org/10.1007/BF00645188
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00645188